The present application is based on Japanese Patent Applications No. 2001-73848 and No. 2001-95696, the entire contents of which are incorporated herein by reference.
The present invention relates to an ink-jet recording apparatus provided with main and auxiliary two ink tanks (a main tank and a subtank) for supplying ink to a recording head and its ink supply method.
An ink-jet recording apparatus is generally provided with a recording head mounted on a carriage and moved in a direction of the width of recording paper and a paper feed device for relatively moving recording paper in a direction perpendicular to a direction in which the recording head is moved.
In such an ink-jet recording apparatus, printing is performed on recording paper by jetting an ink droplet from a recording head based upon print data.
A recording head that can jet each ink in black, yellow, cyan and magenta is mounted on a carriage, not only the printing of text by black ink but full color printing are enabled by varying a rate of jettings of each ink.
Therefore, ink cartridges that supply each ink to the recording head are arranged in the main body of the recording apparatus.
In a normal ink-jet recording apparatus, each ink cartridge in which ink in one of black, yellow, cyan and magenta is stored is mounted on a carriage and is moved together with the carriage.
In the meantime, for example, in this type of recording apparatus provided for an office or for service, an ink cartridge having large capacity in which the above-mentioned each ink is stored is not arranged on a carriage and is arranged on the main body of the recording apparatus to correspond to a relatively large quantity of printing.
A recording apparatus of a type that a main tank as an ink cartridge is arranged on the main body of the recording apparatus (a cartridge holder) and a subtank is arranged on a carriage on which a recording head is mounted is also provided. Ink is supplied from each main tank to each subtank via an ink supply tube and further, ink is supplied from each subtank to each recording head.
In the latest recording apparatuses, to enhance a recording rate, a carriage is moved at high speed.
In such a recording apparatus, the pressure of inside ink varies by the extension or the bending of an ink supply tube due to the acceleration or the deceleration of the carriage and the jetting of an ink droplet from a recording head is made unstable.
Therefore, an open type ink supply method of opening a subtank to the air, discharging the above-mentioned varied pressure from the opening and supplying ink stored in the subtank to a recording head according to difference in an ink head is adopted.
However, the open type ink supply method has the following problems. That is, the open type ink supply method has a problem that as the subtank is open to the air, bubbles are included in ink in the subtank when ink is supplied, a degree of the deaeration of ink supplied to the recording head cannot be guaranteed and satisfactory printing cannot be realized.
There is also a problem that as ink is supplied from the subtank to the recording head according to difference in a head of ink in the subtank, the height of the subtank is required to be sufficiently secured and the whole subtank is large-sized.
The invention is made to solve such technical problems and the object is to provide an ink-jet recording apparatus as well as ink supplying method in which satisfactory printing can be realized and the whole subtank can be miniaturized.
The ink-jet recording apparatus according to the invention made to achieve the object is provided with a reciprocating carriage; a recording head mounted on the carriage for jetting an ink droplet corresponding to print data; a main tank for supplying ink to the recording head; and a subtank mounted on the carriage and connected to the main tank and the recording head, the subtank including an upper tank having an ink outlet for leading ink to the recording head, and a lower tank communicating with the upper tank and having an ink inlet for leading ink from the main tank by pressure of a pump, wherein the lower tank is elastically deformable according to variation of an internal pressure thereof.
As the ink-jet recording apparatus according to the invention is configured as described above, ink in the main tank flows into the lower tank of the subtank according to pressure of a pump when ink is supplied and after the ink further flows from the lower tank into the upper tank, it is supplied from the upper tank to the recording head.
At this time, when the variation of pressure occurs in the lower tank (in ink in an ink supply tube connecting the main tank and the subtank), the lower tank is elastically deformable according to the variation of the internal pressure (the volume) and the variation of the pressure (the volume) is absorbed.
Therefore, as ink from the main tank can be supplied to the recording head according to a closed type ink supply method, bubbles are not included in ink in the subtank when ink is supplied differently from heretofore, a degree of the deaeration of ink is guaranteed and satisfactory printing can be realized.
Also, as ink can be supplied from the subtank to the recording head by negative pressure provided on a side of the recording head, the height of the subtank can be reduced and the whole subtank can be miniaturized.
In this case, it is desirable that at least a part of a tank wall formed on the lower tank is made of an elastic film.
As the tank wall is configured as described above, a part of the tank wall is elastically deformable according to the variation of pressure in the lower tank when the pressure in the lower tank varies.
The elastic film is formed by a material which is flexible, resistant to ink and impermeable to moisture and gas.
As the elastic film is configured as described above, the subtank having the elastic film impermeable to moisture and gas and excellent in flexibility and resistance to ink can be acquired.
It is desirable that a check valve is arranged in the upper tank and opened by negative pressure provided on a side of the recording head.
As the check valve is configured as described above, negative pressure is generated on the side of the recording head, the check valve is opened and ink can be supplied from the main tank to the recording head via the subtank.
It is desirable that the ink jet recording apparatus is further provided with an ink amount detecting device detectable an ink amount in the subtank based upon an amount of elastic deformation thereof.
As the ink amount detecting device is configured as described above, an amount of the elastic deformation of the subtank is detected by the ink amount detecting device and the ink amount in the subtank is controlled.
Pneumatics generated by a pneumatic pump may be applied to the main tank so that ink is supplied to the main tank to the subtank.
As the ink-jet recording apparatus according to the invention is configured as described above, ink can be sequentially supplied from the main tank to the subtank, exceeding printing and the throughput can be enhanced.
A diaphragm pump may be provided at an intermediate position between the main tank and the subtank for supplying ink from the main tank to the subtank according to increase or decrease of an internal volume of the diaphragm pump.
As ink in the main tank is supplied to the subtank by the diaphragm pump when ink is supplied because of such configuration, the main tank is not required to be pressurized in case ink is supplied from the main tank to the subtank, and an ink pack that can resist pressurization and a mechanism for controlling pressurization are not required.
Therefore, as the number of controlled elements can be reduced, a control system can be simplified.
As a pressure chamber is not required to be formed in the main tank, the structure of the main tank can be simplified.
Further, as the outside dimension of the main tank is reduced because no pressure chamber is required in the main tank, the whole recording apparatus can be miniaturized.
It is desirable that a plurality of the main tanks, a plurality of the subtanks and a plurality of the diaphragm pumps are provided.
Ink is supplied from each main tank to each subtank by each diaphragm pump because of such configuration.
In the recording apparatus with the above configuration, it is desirable that a plurality of pump drivers are provided, each of which has a link mechanism corresponding to the diaphragm pumps, wherein the pump drivers are driven by a common motor having a rotation shaft for selectively driving each diaphragm pump.
A motor is not required every diaphragm pump because of such configuration, the number of parts is reduced, the whole structure is simplified and the cost can be reduced.
It is desirable that coupling members are provided to an outer surface of the rotation shaft and the coupling members are selectively coupled to the link mechanisms of the pump drivers.
As the rotation shaft is configured as described above, the link mechanism is selectively coupled to the rotation shaft via each coupling member.
It is desirable that the coupling members are arranged at a predetermined interval in a circumferential direction and an axial direction of the rotation shaft.
As the rotation shaft is configured as described above, the link mechanism is selectively coupled to the rotation shaft via each coupling member located at a predetermined interval in the circumferential direction and the axial direction of the rotation shaft.
Further, it is desirable that each coupling member of the rotation shaft is provided as a driving intermittent gear; and the link mechanism of each pump driver includes a driven intermittent gear corresponding to each driving intermittent gear.
As the coupling member is configured as described above, the link mechanism is coupled to the rotation shaft by the engagement of intermittent gears.
The link mechanism includes a first link arranged in a direction of the outside diameter of the rotation shaft so as to be turned and having the driven intermittent gear at one end of the first link; and a second link turnably and swingably coupled to another end of the first link where the driven intermittent gear is not provided, wherein an internal volume of the diaphragm pump is increased or decreased in accordance with a turning and swing of the second link; and a common pivot part of the second link and the first link is urged by a spring in a direction in which the common pivot part approaches the diaphragm pump.
As the link mechanism is configured as described above, the intermittent gear of the rotation shaft and the intermittent gear of the first link are selectively engaged as a result of the following turning and an arbitrary diaphragm pump is selected when the rotation shaft in an initial state of pump selection is turned in a direction in which the second link separates from the diaphragm pump. In this case, as the rotation shaft is turned in a state in which the second link separates from the diaphragm pump, the internal volume of the diaphragm pump is not increased or decreased.
In the meantime, when the rotation shaft in an initial state of pump driving is turned in a direction in which the second link approaches the diaphragm pump, the intermittent gear of the rotation shaft and the intermittent gear of the first link are engaged as a result and the diaphragm pump is driven (ink is discharged). In this case, the diaphragm pump is contracted and the internal volume of the pump is decreased.
Also, when the rotation shaft is turned in a direction in which the second link separates from the diaphragm pump after the discharge of ink from the diaphragm pump, the diaphragm pump is driven (ink is sucked) as a result. In this case, the diaphragm pump is extended and the internal volume of the pump is increased.
It is desirable that a pin for regulating the turning and the swing of the second link is provided.
As the link mechanism is configured as described above, the turning/the swing of the second link is regulated by the pin.
It is desirable that a long hole fitted to the pin is provided to the second link.
As the link mechanism is configured as described above, the swing of the second link is regulated by fitting the pin and the long hole.
The motor is rotatable in both the normal and reverse directions of rotation.
As the motor is configured as described above, pump selecting operation and pump driving operation are executed by the normal rotation and the reverse rotation of the motor.
It is desirable that the diaphragm pump is selectively driven by the normal or reverse rotation of the motor to thereby supply ink from the main tank to the subtank.
Owing to such configuration, the selecting and driving operation of the diaphragm pump is executed by the engagement of the intermittent gears according to the normal rotation and the reverse rotation of the motor.
Therefore, as the selecting and driving operation of each diaphragm pump can be realized by the normal rotation and the reverse rotation of the motor, the prompt supply of ink to each subtank can be realized.
In the meantime, there is provided a method for supplying ink from a main tank to a recording head via a subtank of an ink-jet recording apparatus provided with a reciprocating carriage, a recording head mounted on the carriage for jetting an ink droplet corresponding to print data, a main tank for supplying ink to the recording head and a subtank mounted on the carriage while connected to the main tank and the recording head, and having an upper tank and a lower tank mutually communicating therebetween, wherein when ink is supplied from the main tank to the recording head, the lower tank is elastically deformable according to a variation of internal pressure thereof.
Owing to such a method, as ink from the main tank can be supplied to the recording had according to a closed type ink supply method, an ink-jet recording apparatus in which bubbles are not included in ink in a subtank when ink is supplied as heretofore, a degree of the deaeration of ink is guaranteed and satisfactory printing is realized can be acquired.
Further, as ink can be supplied from the subtank to the recording head by negative pressure generated on the side of the recording head, an ink-jet recording apparatus in which the dimension in height of a subtank can be reduced and the whole subtank can be miniaturized can be acquired.
A pneumatic pump is arranged in the main tank; and pneumatics generated by the pneumatic pump are applied to the main tank so that ink is supplied to the main tank to the subtank.
Owing to such a method, as ink can be sequentially supplied from the main tank to the subtank, executing printing, the throughput can be enhanced.
A diaphragm pump is provided at an intermediate position between the main tank and the subtank for supplying ink from the main tank to the subtank according to increase or decrease of an internal volume of the diaphragm pump.
Owing to such a method, as ink in the main tank is supplied to the subtank by the diaphragm pump when ink is supplied, the main tank is not required to be pressurized in case ink is supplied from the main tank to the subtank, and ink pack resistant to pressurization and the mechanism for controlling the pressurization are not required.
Therefore, as the number of controlled elements can be reduced, a control system can be simplified.
Further, as the pressure chamber is not required to be formed in the main tank, the structure of the main tank can be also simplified.